1. Field of the Invention
This invention relates to the field of projection devices and more particularly to the field of heads-up displays for use in helmets. More particularly, the present invention relates to the field of projection devices in small, lightweight helmets for use by pilots which use edge emitting devices provided on thin film electroluminescent sources.
2. Description of the Prior Art
The utilization of a projection device such as a heads-up display in a helmet, is well known in the prior art. Such projection devices are typically used to transmit information to the pilot of an aircraft, especially a military aircraft, regarding flight instructions, flight conditions, and the location of other aircraft, targets, and landing facilities.
One of the advantages of a heads-up display is its ability to permit the pilot to perform two functions at the same time. The pilot can continuously view information presented by the heads-up display. At the same time, the pilot can look through the heads-up display to read the controls on the operating panel or visually examine conditions outside the aircraft by looking out the cockpit window.
Although heads-up displays offer many advantages to the pilot, the mechanisms for creating the display are often times heavy and bulky. When the heads-up display is applied to a helmet, the helmet necessarily becomes larger and heavier. Such helmets are frequently awkward to wear and may provide an unacceptable stress on the pilot's neck. Consequently, there is a need for a heads-up display projection device for use in a helmet which is small and lightweight so as to minimize these potential problems to the wearer.
The military presently uses pilot helmets that incorporate a one square inch CRT screen that can be placed in front of one of the pilot's eyes to provide vast quantities of information for the safe and proper operation of the aircraft. A significant drawback to the use of a CRT screen in the helmet is that it is heavy and needs a 1000-volt power supply for its operation. This makes the helmets bulky.
Means for providing the pilots the same or more information in a lighter weight packaging is needed. The improved heads-up display should include use of a transparent screen enabling the pilots to perceive all the necessary information transmitted on the screen without detracting from the pilot's ability to see from the aircraft itself.